Telomeres

Aging is a universal biological phenomenon in eukaryotes, but why and how we age still remain mysterious. It would be of great biological interest and practical importance if we could uncover the molecular mechanism of aging, and find a way to delay the aging process while maintaining physical and mental strengths of youth. Histone deacetylases (HDACs) such as SIR2 and RPD3 are known to be involved in the extension of lifespan in yeast and Caenorhabditis elegans.

P. anserina mutants with impairments in complex IV (COX) of the respiratory chain are characterized by an increase in lifespan. Examples are the nuclear grisea mutant with a moderate lifespan extension (60%) and the immortal extranuclear ex1 mutant. Here we report data demonstrating that in mutant ex1 the level of the alternative oxidase (PaAOX) is significantly higher than in mutant grisea. PaAOX levels appear to be reversely dependent on COX activity.

Replicative senescence is thought to be a significant barrier to human tumorigenesis, which in human fibroblasts, and many other cell types, can be overcome experimentally by combined loss of function of p53 and Rb 'pathways'. To avoid the confounding pleiotropic effects of HPVE7 frequently used in such studies, here we have employed retroviral vectors over-expressing CDK4 or CDK6 as a more representative model of naturally-occurring mutations targeting the Rb pathway.

PURPOSE: To investigate the feasibility, toxicity, cosmetic outcome, and local control of high-dose-rate (HDR) brachytherapy alone without whole breast external beam irradiation for early-stage breast carcinoma. METHODS AND MATERIALS: Between June 1997 and August 1999, 32 women diagnosed with a total of 33 AJCC Stage I/II breast carcinomas underwent surgical breast excision and postoperative irradiation using HDR brachytherapy interstitial implantation as part of a multi-institutional clinical Phase I/II protocol.

PURPOSE: To describe herpes zoster ophthalmicus in relation to the anatomy, pathophysiology, course, diagnostic considerations, and management for the primary care provider. DATA SOURCES: Actual case study supplemented with an extensive review of current scientific and psychosocial literature. CONCLUSIONS: Herpes zoster ophthalmicus (HZO) is an extension of a herpes zoster (HZ) infection involving the fifth cranial (trigeminal) nerve, which results from the reactivation of a latent varicella virus among individuals who had contracted a varicella infection sometime within their lifespan.

The vast majority of breast cancers are carcinomas that arise from mammary epithelial cells (MECs). One of the key early events in tumorigenic transformation is the ability of cells to overcome replicative senescence. However, the precise genetic changes that are responsible for this event in MECs is largely unknown. Here, we report that Bmi-1, originally identified as a c-Myc cooperating oncoprotein, can bypass senescence, extend the replicative life span, and immortalize MECs. Furthermore, Bmi-1 was overexpressed in immortal MECs and several breast cancer cell lines.

Normal human cells have a finite proliferative potential in vitro. However, some DNA viral proteins, such as SV40 Tg, can alter this and extend the lifespan after which the cells enter crisis, a period when massive cell death occurs. Based on these observations, a two-stage model for cellular senescence has been proposed with a distinct function for each stage.

Aging is characterized by a progressive decline of cellular functions. The aging liver appears to preserve its function relatively well. Aging is associated in human liver with morphological changes such as decrease in size attributable to decreased hepatic blood flow. Ultrastructural analysis of the human liver has revealed that the integrity of mitochondria and enzymatic activity remain mostly unchanged with aging. Reactive oxygen species (ROS) are involved in the aging process and result mainly from nonenzymatic processes in the liver.

The nematode Caenorhabditis elegans is an important model for studying the genetics of ageing, with over 50 life-extension mutations known so far. However, little is known about the pathobiology of ageing in this species, limiting attempts to connect genotype with senescent phenotype. Using ultrastructural analysis and visualization of specific cell types with green fluorescent protein, we examined cell integrity in different tissues as the animal ages.

Caloric restriction (CR) may retard aging processes and extend lifespan in organisms by altering energy-metabolic pathways. In CR rodents, glucose influx into tissues is not reduced, as compared with control animals fed ad libitum (AL), although plasma concentrations of glucose and insulin are lower. Gene expression profiles in rodents have suggested that CR promotes gluconeogenesis and fatty acid biosynthesis in skeletal muscle. In the liver, CR promotes gluconeogenesis but decreases fatty acid synthesis and glycolysis.